Remote control apparatus for maintaining in-vessel components in a structure having an inner torus space

ABSTRACT

A remote control apparatus for maintaining a tokamak type nuclear fusion reactor comprises a rail having a plurality of arcuated links to be extended in a circumferential direction and a plurality of joints for pivotally connecting the adjacent arcuated links, a vehicle running on the rail extended so as to form a continuous arc with its center substantially coinciding with the center of the torus space, and at least one handling device mounted on the vehicle, for handling the in-vessel components. The remote control apparatus is further provided with a rail housing device for receiving the arcuated links in a folded state when they are not in use, a rail mounting device for sending out said arcuated links in succession into the torus space, extending them so that they form a continuous arc and supporting the arcuated link on the proximal end of the rail, and a rail supporting device for supporting the central portion of the rail extended in the torus space.

This is a division of Ser. No. 654,056, filed on Feb. 12, 1991 of U.S.Pat. No. 5,173,248.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a remote control apparatus for maintainingin-vessel components in a structure having an inner torus space, and inmore particular to a remotely controlling maintenance apparatus adaptedfor a tokamak type nuclear fusion reactor.

2. Description of the Related Art

With a nuclear fusion reactor in which a D-T reaction occurs, themaintenance of the in-vessel components must always be remotelycontrolled in order to protect the operator from radiation produced inthe reactor after it begins to be run.

As shown in FIG. 34 the tokamak type nuclear fusion reactor has a hollowdonut shape vessel 1, the torus space 2 of which has an outer diameterof substantially 10 meters and which is covered with a shield member 3having a thickness of several meters. The peripheral components such asa toroidal coil 4 and a poloidal coil 5 surround the inner torus space 2in a complicated manner. Accordingly, it is necessary to insert amaintenance device housed in a cask 8 disposed outside of the reactorinto the torus space 2 through maintenance ports 9 each extendingradially of the torus space 2 and further to move the maintenance devicein the circumferential directions in the space 2 so that the maintenancedevice is accessible to the in-vessel components such as diverter plates6 and first wall armor tiles 7 without interference with the peripheralcomponents. Since the in-vessel components include very heavy componentssuch as the diverter plate weighing more than 1 ton, these heavycomponents impose many technical problems on a maintenance device.

The conventional maintenance devices are classed into two types. One ofthem has, as shown in FIG. 35, a cantilever type multi-joint arm(articulated arm) 10 which has its base joint disposed at the outside ofthe reactor. The arm 10 is inserted in the torus space 2 through themaintenance port 9 to have access to the in-vessel components. Themaintenance devices of this type have been used in the United states andEurope. However, as the vessel becomes larger and larger, thearticulated arm becomes longer and longer. In addition, the in-vesselcomponents to be handled become heavier. These make it difficult toaccurately set the distal end of the articulated arm 10 at a requiredposition. Further, the maintenance device of this type has the problemthat its operational efficiency and reliability are lowered because thelong overall articulated arm 10 must be moved in the narrow torus space2 at each time when the in-vessel components are handled. An example ofthe maintenance devices of this type is disclosed in the thesis titled"THE TFTR MAINTENANCE MANIPULATOR" by M. Selig et al (Proceedings of aTechnical Committee Meeting on Robotics and Remote Maintenance Conceptsfor Fusion Machines -Karlsruhe, 22-24 February 1988- issued by TheInternational Atomic Energy Agency).

The maintenance device of the other type has a vehicle which runs on arail laid in the torus space so that the vehicle is accessible to thein-vessel components to handle them. The maintenance device of this typehas the features that the positioning of the vehicle at the time ofaccess to the in-vessel components is accurately carried out due to onedegree of freedom defined by the running of the vehicle on the rail andthat the in-vessel components are efficiently transported. An example ofthe rail-mounted devices is disclosed in the thesis titled "VEHICLECONCEPT FOR NET IN-VESSEL INSPECTION AND MAINTENANCE" by D. Maisonnier(Proceedings of a Technical Committee Meeting on Robotics and RemoteMaintenance Concepts for Fusion Machines--Karlsruhe, 22-24 February1988, issued by The International Atomic Energy Agency).

Maisonnier's system comprises two boom rails extended through 90° in thetorus space. The boom rails are inserted therein through the opposedmaintenance ports and connected at their front ends to form avehicle-guiding rail extending through 180° in the torus space. Eachboom rail comprises three curved box-like link elements seriallyarticulated at their ends to one after another. Maisonnier's thesis onlybriefly describes that the joint of each link member is driven by alever mechanism and depicts that each link element contains a drive rodfor driving the corresponding joint. The vehicle moves radiallyoutwardly along the rail.

In the rail system, the semi-circularly extended rail is supported onits both ends so that the rigidity can be made larger than thearticulated arm as shown in FIG. 35.

However, the semi-circularly arcuated rail is supported only on bothends and it cannot be supported at its central portion because thevehicle is moved along the radially outer side of the rail. When a heavyin-vessel component is handled by the vehicle at the central portion ofthe rail, a large bending moment and a large torsional moment areexerted on and at the vicinity of the end portion of the rail at whichthe rail is supported so that the rail is likely to be bent. Therefore,the arcuated links forming a boom rail must be rendered large in size aswell. For example, when the radius curvature of the rail is 5,200 mm,the height, the width and the length of the links should be 1,000 mm,150 mm and 2,250 mm, respectively. A large space for storing the rail isrequired. Further, the rail requires complicated mechanisms such aslever mechanisms for extending and shrinking the rail and drive rods.This requires complicated control when the rail is extended in thevessel.

A circular arc telescope type rail system can be used to extend a railin the torus space. However, it has the drawback that its reliability islowered when it remains exposed under radiation of a high level during along maintenance time, because an actuator or a complicated drivingmechanism must be provided in the rail.

Further, the thickness of the telescope rail is not constant throughoutthe whole length. This makes it difficult to guide and move the vehiclein a stable state and makes the structure and the control of the railcomplicated.

SUMMARY OF THE INVENTION

The object of the invention is to provide a remote control maintenanceapparatus which has a high operational efficiency and reliability and isparticularly useful for a tokamak nuclear fusion reactor.

In order to attain the object, this invention provides a remote controlapparatus for maintaining a structure which comprises a vessel having atorus space formed therein and a plurality of maintenance portsextending radially for causing the torus space to communicate with theoutside of the vessel and components arranged in the vessel, comprising:

a rail having generally similarly arcuated links pivoted to one afteranother and extensible in the circumferential directions in the torusspace, the links forming, in the torus space, a continuous semi-circulararc having a center substantially coincident with the center of thetorus space when the links are extended;

a vehicle carrying at least one manipulator for handling the componentsand guided along the rail extended in the torus space;

rail housing means arranged outside of the vessel, for housing the railwhen the remote control device is not used;

rail mounting means carrying the last link of the rail and delivering,into the torus space, the links housed in the rail housing means fromthe first link to the last link in succession through one of themaintenance ports and causing the links to form the continuoussemi-circular arc; and

a rail supporting device inserted in the torus space through anothermaintenance port adjacent to the first mentioned maintenance port, forsupporting the central portion of the rail.

In this remote control maintenance apparatus, the rail comprises aplurality of links and joints for articulating the adjacent links andeach provided with a locking mechanism for locking the respective linkat the position in which the arcuated links form the semicircular arcand the rail is transmitted into the torus space by means of atransmitting mechanism. In this respect, the arcuated links can behoused in the rail housing means having a limited space. Further, whenthe rail is transmitted into the torus space, the links are deliveredfrom the first one to the last one in succession by means of the railmounting device, whereby the links pass through a narrow maintenanceport easily. The rail formed in a continuous circular arc shape issupported by means of the rail supporting device inserted from anothermaintenance port adjacent to the first mentioned maintenance port. Thisnot only renders the rigidity of the rail high and the movement of thevehicle stable but also minimizes the overall apparatus.

Further, the stable operation of the vehicle makes the operation of themanipulator mounted on the vehicle stabilized, enabling the componentsto be handled at a high operational efficiency.

Additional objects and advantages of the invention will be set forth inthe description which follows, and in part will be obvious from thedescription, or may be learned by practice of the invention. The objectsand advantages of the invention may be realized and obtained by mean ofthe instrumentalities and combinations particularly pointed out in theappended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of the specification, illustrate presently preferred embodiments ofthe invention, and together with the general description given above andthe detailed description of the preferred embodiments given below, serveto explain the principles of the invention.

FIG. 1 is a schematic perspective view of one embodiment of the remotecontrol maintenance apparatus according to this invention;

FIG. 2 is a schematic plan view of a rail in a state in which the railis housed in a cask in this embodiment;

FIG. 3 is a perspective view of a joint of the rail of this embodiment;

FIG. 4 is a schematic perspective view of vehicle driving means of thisembodiment;

FIG. 5 is a side view of a first slide link and a second slide linkhoused on the cask;

FIG. 6 is a schematic plan view showing the state in which the distalend of the rail is extended in a maintenance port together with thefirst slide link;

FIG. 7 is a schematic plan view showing the state in which an supportarm and the first link are set in position in a torus space;

FIG. 8 is a schematic plan view of a link roller holder mounted on thefirst slide link;

FIGS. 9, 10, 11 and 13 show the steps of extending the rail of thisembodiment;

FIG. 12 is a perspective view of a joint locking mechanism and itsdriving mechanism of this embodiment;

FIG. 14 is a side view of a rail supporting device of this embodiment;

FIG. 15 is a perspective view of the detail of the distal end portion ofthe rail supporting device;

FIG. 16 is a plan view of a mechanism for fixing the distal end of therail in the opposed port;

FIG. 17 is a perspective view of the detail of the vehicle;

FIG. 18 is a side view of a diverter plate showing how to exchange thesame in this embodiment;

FIG. 19 is a block diagram of the embodiment of the remote controlmaintenance apparatus of FIG. 1;

FIG. 20 is a side view of a manipulator for maintaining armor tiles andits lift;

FIG. 21 shows a transitional state in which the manipulator mountedvehicle passes through a joint of the rail, as an example;

FIG. 22 is a schematic perspective view of the first modification of thevehicle on which a manipulator for maintaining armor tiles haspreviously been mounted;

FIG. 23 is a cross-sectional view along line B--B of FIG. 22;

FIG. 24 is a cross-sectional view along line C--C of FIG. 22;

FIGS. 25 to 27 illustrate the operation of two rings of the manipulatorfor maintaining armor tiles of FIG. 22;

FIG. 28 illustrates the operation of the manipulator for maintainingarmor tiles of FIG. 22;

FIG. 29 shows the degree of freedom of the manipulator for maintainingarmor tiles of FIG. 22;

FIG. 30 is a perspective view of the second embodiment of the vehicle onwhich two manipulators for maintaining armor tiles;

FIG. 31 is a plan view of the housed cable when the rail is housed inthe cask;

FIGS. 32 and 33 are schematic plan views showing how to handle the cablewhen the rail is extended in the torus space;

FIG. 34 is a longitudinal cross-sectional view of a tokamak type nuclearfusion reactor; and

FIG. 35 is a schematic plan view of a conventional remote controlmaintenance apparatus.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows an embodiment of a remote control maintenance apparatusaccording to this invention.

As described above, this remote control maintenance apparatus isintended to maintain the in-vessel components in the tokamak typenuclear fusion reactor 1 which, in general, comprises a vessel forming atorus space 2, casks 8 arranged around the vessel, and four maintenanceports 9 for causing the casks 8 to communicate with the torus space 2(FIG. 34).

The remote control maintenance apparatus disclosed in FIG. 1 is insertedin the torus space 2 through one of the maintenance ports 9. Theapparatus comprises a rail 100 and a vehicle 300 on which a manipulator330 is mounted and which runs on the rail 100. When the remote controlmaintenance apparatus is not used, the rail 100 is contained in a railhousing guide 206 provided in the respective cask 8. When the in-vesselcomponents must be maintained, on the other hand, the rail 100 isextended into the torus space 2 by means of a rail mounting device 200which has a first and second slide links 203, 204 expandable toward thecenter of the torus space 2 to move the rail 100 from the interior ofthe cask 8 into the tours space 2 and a support arm 205, swingablymounted on the front end of the first slide link 203, detachably holdingthe vehicle 300. In this connection, the rail housing guide 206 and therail mounting device 200 are also the elements of the remote controlmaintenance apparatus.

By means of the rail mounting device 200, the rail 100 is moved from therail housing guide 206 into the torus space 2 along the first and secondslide links 203 and 204, and extended by the length corresponding tohalf the circumferential length of the torus space 2 or itscircumferential angle of 180°, and thereafter the rail 100 is rigidlyfixed by one or more rail supporting devices 250 inserted in the torusspace 2 through one or more maintenance ports a adjacent to each otherthrough which the remote control apparatus or remote control apparatusesare guided.

The remote control maintenance apparatus can be provided with rails 100extending, in combination, by 360° along the circumference of the torusspace 2 by using two rail mounting devices 200, or can be provided witha rail 100 extending half the circumferential length of the torus spaceor its circumferential angle of 180°. In both cases, the laying of therail 100 and the maintenance by using the vehicle 300 are similarlycarried out.

Explanation of the remote control maintenance apparatus will be madeaccording to the following steps:

1. the step in which the arcuated rail is housed in the cask,

2. the step in which the apparatus is moving in the maintenance port 9,

3. the step in which the apparatus is moving in the torus space 2,

4. the step in which the apparatus is extended and supported by the railsupporting device 250, the state being shown in FIG. 1,

5. the step in which the vehicle 300 is moved along the rail 100 and thediverter plate 6 is changed by means of the manipulator 330 mounted onthe vehicle 300,

6. the step in which the apparatus is restored in the cask 8,

7. the step in which a manipulator 360 (described later) for maintaininga first wall 7 of an armor tile, and

8. the operation of a cable.

1. The Step in which the Rail 100 is Housed in the Cask

FIG. 2 is a plan view of the rail 100 in the state in which it is housedin the cask.

In this embodiment, the rail 100 comprises six arcuated links 101a,101b, 101c, 101d, 101e and 101f arranged from the distal end toward theproximal end of the rail 100 in this order and joints 102a, 102b, 102c,102d, 102e and 102f arranged from the distal end toward the proximal endof the rail 100 in this order, for pivotally connecting adjacent links.It is noted that referential numerals 101 and 102 will be used for thelink or links and the joint or joints when they are not specified. Asshown in FIG. 2, the links 101 can rotate radially outwardly of the arcdefined by each link 101 itself around the corresponding joints 102 butcannot pivot radially inwardly of the arc beyond a continuoussemicircular arc formed by all the links 101. When each link 101 has aradius of curvature of 4500 mm, the width of 250 mm and the height of500 mm can be selected. In this case, each link 101 may have a hollowstructure with a wall thickness of 20 mm by selecting a suitablematerial.

A swing link 201 is connected to the link 101f at the proximal end ofthe rail 100 by means of the joint 102f and is swingably supported onthe upper surface of a rail carriage 202 which is a part of a railmounting device 200. The rail carriage 202 has means for driving theswing link 201 (the means being not shown), a slide link drivingmechanism (not shown) for driving a first slide link 203 and a secondslide link 204 both adapted to move the rail. The second link 204 ishidden under the first slide link 203 in FIG. 2.

A support arm 205 is pivotally supported on the first slide link 203 soas to be rotated with respect to the first slide link 203 by the drivingmeans (not shown) around an axis substantially coinciding with the axisof the joint 102a. A vehicle 300 is detachably connected to the distalend of the arm 205 by means of a vehicle holding mechanism (not shown).

A maintenance port 9 is provided in front of first slide link 203 on theextension therefrom.

As shown in FIG. 3, a rotatable joint roller 103 is provided under eachjoint 102 so as to be arranged coaxial therewith. The joint roller 103is fitted in a guide groove formed in an arcuated rail-housing guide 206(FIG. 2) and its movement in the radial directions of the arc defined bythe swing link 201 is restricted. The undersurface of each link 101 isslidably supported on the upper surface of the rail-housing guide 206.The distal end portion of the first link 101a of the rail 100 isreceived in the vehicle 300 running on the rail 100. A cable support 401is provided for guiding a cable (later described) which supplies powerto the vehicle 300 and transmits signals between the vehicle 300 and acontrol device. The cable support 401 has a cable receiver 405 having agenerally U shape and pivoted to the joint 102 by a support shaft 406. Alever 404 bridges the upper ends of the cable receiver 405 and is pushedto be turned outside thereof. The cable receiver 405 is provided withthree rollers 405A for preventing the cable from being damaged.

As shown in FIG. 4, a rack 104 is formed on the arcuated inner face ofthe arcuated links 101 and the vehicle is provided with a pinion 301engaging therewith and a driving mechanism or driving means 302comprising such as a servo motor and a reduction device.

FIG. 5 is a side view of rail mounting means 200 facing the maintenanceport 9. The first slide link 203 is supported slidably in its lengthwisedirections on the second slide link 204 disposed thereunder and isdriven by driving means (not shown). The second slide link 204 ismounted slidably in its lengthwise directions on a fixed guide 207 andis provided with driving means (not shown) for driving the second slidelink 204. On the distal end portion of the undersurface of the secondslide link 204 are arranged a plurality of rollers 208 which form abogie structure so that the second slide link 204 is guided on the floorsurface of the maintenance port 9 when the second slide link 204 entersthe maintenance port 9.

2. The Step in which the Rail is Being Moved in the Maintenance Port

FIG. 6 shows the state in which the distal end portion of the rail 100together with the first slide link 203 move toward the center of thetorus space 2 in the maintenance port 9. As shown in FIG. 6, the firstslide link 203 slides on the second slide link 204 and enters themaintenance port 9. At the same time, the swing link 201 is rotatedaround the pivotal axis of the rail carriage 202. The main body of therail carriage 202 is not moved with respect to the fixed guide 207.However, its driving means for the first slide link 203 is beingoperated.

As a result, the links 101 of the rail 100 move forwardly from the firstlink 101a to the last link 101f in succession on the first slide link203 with their joint rollers 103 received in the guide groove 209 formedin the upper surface of the first slide link 203.

After the first slide link 203 has been moved by a predetermineddistance on the second slide link 204 as described above, the secondslide link 204 is transferred by a predetermined distance on the fixedguide 207. The rail 100 leaves the rail housing 206, and all six joints102 are arranged on the first and second slide links 203 and 204 in alinearly extended state in the lengthwise direction of both links 203and 204. In this state, the rail carriage 202 is arranged to theproximal end of the second slide link 204.

In the next step, the driving mechanism of the rail carriage 202 forrotating the swing link 201 is stopped, and the second slide link 204and the rail carriage 202 are simultaneously moved on the fixed guide207. Then, the vehicle 300 at the distal end of the rail 100 enters thetorus space 2. The movement of the second slide link 204 and therotation of the support ar 205 which are effected in synchronism witheach other at predetermined speeds are adjusted so as to avoid theinterference of the vehicle 300 and the support arm 205 with the innerwall of the torus space 2. When the center of the arcuated first link101a substantially coincides with the center 0 of the torus space 2, thevehicle 300 and the support arm 205 are stopped operating, as shown inFIG. 7.

As described above, the substantial coincidence of the pivotal axis ofthe support arm 205 with the rotating axis of the joint of 102a of thefirst link 101a allows the link 101a to be rotated in accordance withthe rotation of the support arm 205.

3. The Step in which the Rail is Moved in the Torus Space

Referring to FIG. 8, slidably driving the joint rollers 103 (FIG. 3) inthe guide groove 209 will now be explained. FIG. 8 is shown the railmounting device 200 with the rail 100 removed as shown in FIG. 7. Ajoint roller holder 210 having a crescent cross section can be moved inthe guide groove 209 so that its lateral and vertical movements withrespect to the guide groove 209 are restricted. The joint roller guide210 is moved in the guide groove 209 at a predetermined stroke A bymeans of a linear guide (not shown) and driving means (not shown) androtated in the guide groove 209 by means of its rotatable hold means(not shown) and its driving means (not shown).

The extending operation of the rail 100 in the torus space 2 by means ofthe joint roller holder 210 will now be explained with reference toFIGS. 7 to 11.

In the state as shown in FIG. 7, the joint roller holder 210 holds thejoint roller 103b provided on the lower portion of the joint 102b withdepressed inner surface of the joint roller holder facing the center ofthe torus space 2. As described above, the vehicle 300 is fixed to thesupport arm 205. In this state, by operating the driving means of thevehicle 300, the link 101a is extended from the distal end of thevehicle 300, while moving the joint roller holder 210 toward the centerof the torus space 2 by the predetermined distance. At the same time,the rail carriage 202 at the proximal end of the rail 100 is caused toslide along the second slide link 204 by the same distance as the jointroller holder 210. In consequence, the whole rail 100 on the first andsecond slide links is moved toward the center of the torus space 2 andis stopped when the joint 102a arrives at the proximal end of thevehicle 300.

The joint roller holder 210 is slightly displaced toward the cask 8.After being separated from the joint roller 103b, the joint rollerholder 210 is rotated through 180° so as to direct its depressed innerface toward the cask 8 and then receives the joint roller 103c providedon the next joint 102c.

As shown in FIG. 9, the joint roller holder 210 with the joint roller103c held therein is rotated so that the depressed inner face isdirected toward the center of the torus space 2 again.

In the next step, the driving means of the vehicle 300 remainsstationary. The joint roller holder 210 is caused to slide toward thecenter of the torus space 2 and the rail carriage 202 is also caused toslide along the second slide link 204 by the same distance as the jointroller holder 210 at the same time. The overall rail 100 is moved towardthe center of the torus space 2 and the link 101b is rotated around thejoint 102a from a transient state as shown in FIG. 10 to the final stateas shown in FIG. 11 in which the links 101a and 101b cooperate to assumea continuous arc having a center of curvature substantially coincidentwith the center O of the torus space 2.

Referring to FIG. 12, the explanation will now be made to the way forlocking the joint and its operation.

As shown in FIG. 12, a hook 105 is housed in an end of the right sidelink 101 which is adjacent to the left side link 101. A support shaft106 with the hook 105 is rotatably supported so as to be directedradially of the arcuated link 101. A narrow rectangular projection 107is formed on the end of the support shaft 106 which is at the inner sideof the link 101 so that it diametrically crosses the end. The projection107 is directed in the circumferential direction when the hook 105engages with and disengages from a pin 108 housed in the left side link101 adjacent to the right side link 101.

Referring to FIG. 12 again, an operation member 303 having a narrowrectangular groove 303a diametrically formed therein is rotatablysupported by the proximal end of the vehicle 300. The groove 303a isdesigned to engage with the projection 107, when the link 101 is at aposition as shown in FIG. 11. As shown in FIG. 11, a driving mechanism304 for the operation member 303 is provided on the proximal end of thevehicle 303.

In the state as shown in FIG. 11, therefore, the links 101a and 101b arefirmly connected to each other by rotating the operation member 303though 180° for allowing the groove 303a to be rotated through the sameangle and engaging the hook 105 with the pin 108 so that both links donot rotate with respect to each other.

In the next step, the joint roller holder 210 is rotated through 180° toallow its depressed inner face to be directed toward the cask 8 and thelink 101a is further extended toward distal end thereof by the drivingmeans of the vehicle 300. At the same time, the joint roller holder 210and the rail carriage 202 are moved toward the cask 8 by a the samepredetermined distance. When the joint 102b arrives at the rotating axisof the support arm 205, the joint roller holder 210 is rotated through180° to take the position as shown in FIG. 13 in which the first link101a projects from the vehicle 300 as compared with FIG. 7.

The above-mentioned operation is repeated until the rail 100 in themaintenance port 9 is extended in a continuous arc shape in a lockedstate in the torus space 2.

4. The Step in which the Rail is Supported by the Rail Supporting DeviceAfter Being Extended in the Tours Space

In FIG. 1 (as already mentioned), is shown the state in which theextended rail 100 is supported by the rail supporting device 250.

As shown in FIGS. 14 and 15, the rail supporting device 250 comprises abase 251 located externally of the reactor, a side link assembly 252slidable in two steps by comprising a first slide link 252a slidablealong the base 251 in the radial directions of the torus space 2 and asecond slide link 252b slidable along the first slide link 252a, adriving mechanism (not shown), a guide roller 254 provided on the distalend of the second slide link 252b and swingable by means of a drivingdevice 253 between a position close to the rail 100 and a positionremote therefrom, a rail clamping mechanism 255 opened and closed bymean of a driving mechanism (not shown), and an in-vessel componenttransporting mechanism 256 movable along the directions in which theslide link assembly 252 is extended and shrunk.

When the rail 100 is extended in the torus space 2 according to theabove-mentioned steps, the slide link assembly 252 of the railsupporting device 250 is introduced through the adjacent maintenanceport 9 into the torus space 2 and its distal end is set in position inthe torus space 2. During the extension of the rail 100, the guideroller 254 is abutted against the undersurface of the rail 100. Afterthe extension, the rail clamping mechanism 255 is arcuated by thedriving mechanism (not shown) to hold the projection 109 (FIG. 15)formed between the adjacent joints on the outer peripheral surface ofthe rail 100. Next, the guide roller 254 can be swung by means of thedriving device 253 to such a position shown by phontom lines in FIG. 15so that the guide roller 254 does not hinder the running of the vehicle300.

Referring to FIG. 16, the fixing of the distal ends of a pair of railswill now be explained.

The rail mounting assembly comprises a first rail mounting device 200having the same structure as mentioned above and a second rail mountingdevice 200 and introduced into the torus space 2 through anothermaintenance port 9 which is oppositely aligned with the maintenance port9 (FIG. 1) through which the first rail mounting device 200 passes. Thefirst link 101a of the rail 100 extended by the first rail mountingdevice 200 is fixed by the second rail mounting device 200, and thefirst link 101a' of the rail 100' extended by the second rail mountingdevice 200 is likewise fixed by the first mounting device 200.

In other words, by rotating the link 101f around the joint 102e andmoving the rail carriage 202 forwardly, a rail holding device (notshown) provided on the distal end of the swing link 201 of the firstrail mounting device 200 is moved to the facing distal end of the firstlink 101a' of the rail 100' to fixedly hold it. Thereafter, the joint102e is locked to the vehicle 300. Likewise, a rail holding device (notshown) of the second rail mounting device 200 fixedly holds the distalend of the first link 101a of the rail 100, and the corresponding jointis also locked to the vehicle 300. In this way, the rails 100 and 100'are firmly supported at four points and form a circular track for thevehicle 300.

Where, on the other hand, only one rail mounting device 200 is used toextend the rail 100 over half the circumferential length (FIG. 1), tworail supporting devices 250 are introduced through a maintenance port 9oppositely disposed to the rail mounting device 200 and anothermaintenance port 9 facing the side of the rail 100 so that they hold thefirst link and a middle link, respectively to ensure a rigid supportingof the rail 100 at three points. The rail 100 is extended in the torusspace 2 and is held in a stable state.

It is noted that the rail 100, in FIG. 1, is supported by the railsupporting device 250 inserted through the maintenance port 9 adjacentto the rail mounting device 200 but another maintenance port 9 throughwhich another rail supporting device passes is omitted from the figurefor simplicity.

5. The Step in which the Diverter is Exchanged.

As described above, the vehicle 300 has the pinion 301 engaging the rack104 provided on the lateral side of the rail 100 and its drivingmechanism 302 (FIG. 4). As shown in FIG. 17, the vehicle 300 is furtherprovided with a manipulator 330 having a telescopic arm 331 swingable bymeans of a extensible and shrinkable actuator 332 in a planeperpendicular to the rail 100 and its driving mechanism, and the drivingmechanism 304 for operating the locking mechanism of the rail 100.

A plurality of wheels 306 are pivoted to inner surfaces of the channeledframe 305 of the vehicle 300 in such a manner that the horizontal groupsof the wheels 306 rotatably contact the upper and undersurface of therail 100, respectively, and the vertical groups thereof rotatablycontact the inner and outer lateral sides of the rail 100, respectively,so that the joints 102 of the rail 100 can pass the channeled portion ofthe vehicle 300. As described above, the pinion 301 engaging with therack 104 formed on the inner wall of each link 101 of the rail 100 (seeFIG. 4) is driven by means of the driving mechanism 302. The telescopicarm 331 mounted on the frame 305 at its inner side of the torus space 2is provided at its distal end with an end effecter 333 extensible andshrinkable by a driving mechanism (not shown) and having the freedom ofswing, rotation and holding for handling the in-vessel components. Thedriving mechanism 304 for the locking mechanism of the joint 102 isprovided on the proximal end of the frame 305.

On the undersurface of the vehicle 300 is formed the projection for thevehicle holding mechanism provided on the support arm 205.

The exchange of the diverter plate which is one of the in-vesselcomponents will now be explained with reference to FIG. 18.

After the extension and fixing of the rail 100 in the torus space 2according to the steps (1) to (4), the vehicle holding mechanism of thesupport arm 205 is released. The vehicle 300 is moved along the rail 100by driving the pinion 301. Upon arriving at the position above thediverter plate 6 to be exchanged, the vehicle 300 is stopped. As shownin FIG. 18, the telescopic arm 331 is extended or shrunk and swung andthe end effecter 333 is set in position for holding the diverter platein accordance with the freedom of the end effecter itself.

The end effecter 333 is actuated to hold the diverter plate 6 so thatthe end effecter 333 lifts the diverter plate 6 according to the stepsshown by a, b and c in FIG. 18. The vehicle 300 is further moved untilit reaches the position in front of the maintenance port 9 in which therail supporting device 250 is inserted, as shown in FIG. 14. Thetelescopic arm 331 is shrunk and swung to lift the diverter plate 6 tothe position d in FIG. 18. Thereafter, the in-vessel transportingmechanism 256 is sent into the torus space 2 from the maintenance port9. The in-vessel transporting mechanism 256 comprises a carriagesupported by a plurality of the rollers 257 forming a bogie structureand a driving mechanism (not shown). When the mechanism 257 is advanced,the carriage arrives at the position right under the rail 100 totransport an in-vessel component between the carriage and the vehicle300. In the present case, the carriage receives the diverter plate 6from the vehicle 300 and is retracted to transport the diverter plate 6in a maintenance cask (not shown). When the step is reversed, a newdiverter plate 6 can, of course, be mounted in the vessel of the torusspace 2.

6. In the Step in which the Extended Overall Rail is Restored in theCask

The rail mounting device extended in the maintenance port or the reactoris restored in the cask substantially in reverse steps to those of theextension. The steps will now be explained. It is noted that the railextended from another maintenance port is similarly restored in thecorresponding cask.

(i) The vehicle 300 is returned to the position at which the support arm205 is disposed and is fixed thereto by the vehicle holding mechanism.In this case, the manipulator 330 is shrunk to take a predeterminedposture a shown in FIG. 16.

(ii) The guide roller 254 of the rail supporting device 250 is advancedto support the rail 100, and the projection 109 formed on the outerperiphery of the rail is released as shown in FIG. 15.

(iii) The joint 102e of the last link 101f is unlocked as shown in FIG.16.

(iv) The first links 101a and 101a' of the first and second railmounting devices transferred from the opposing maintenance ports arereleased as shown in FIG. 16.

(v) As the rail carriage 202 is toward the cask 8, the swing link 201 isrotated through a predetermined angle so that the last link 101f of therail 100 is rotated through a predetermined angle as shown by thephantom lines in FIG. 16.

(vi) By means of the driving mechanism of the vehicle 300, the next link101 is pulled in at the position at which the next joint 102 isreleased. In synchronism therewith, the rail carriage 202 is moved asshown in FIG. 13.

(vii) The joint 102 of the rail 100 is unlocked as shown in FIG. 12.

(viii) As the rail carriage 202 is moved toward the cask 8, the jointroller holder 210 is actuated to rotate the link of the unlocked jointthrough a predetermined angle as shown in FIG. 11.

(ix) The rail is pulled in by means of the vehicle 300 at the positionat which the next joint 102 is unlocked. In synchronism therewith, therail carriage 202 and the joint roller holder 210 are moved in apredetermined manner as shown in FIGS. 9 and 10.

(x) The steps (viii) and (ix) is repeated so that the links 102 arlinearly arranged in the maintenance port 9 as shown in FIG. 7.

(xi) As the second slide link 204 is retracted, the support arm 205 isrotated through a predetermined angle so that the vehicle 300 enters themaintenance port.

(xii) The second slide link 204 and the rail carriage 202 are returnedto the places where they were housed in the casks 8 and the last link101f is moved along the rail housing guide 206 to be housed therein asshown in FIG. 6.

(xiii) As the first slide link 203 is retracted, the swing link 201 isswung through a predetermined angle to house the rail 100, the firstslide link 203 and the vehicle 300 in the cask as shown in FIG. 2.

To perform synchronous operation of a plurality of driving mechanisms asdescribed above, the servo motors of the driving mechanisms aregenerally controlled so that their rotational angles are set topredetermined values as time passes. However, due to backlash, bending,variation of dimension, variation of frictions and the like of elementsto be controlled, their real positions are likely to be displaced fromthe positions to be set. Such displacement increases positionaldeviation in the position control loop and generates restoring forces tothe positions to be set. When the arcuated links are moved into thetorus space 2 or the like, the directions in which they are restricteddiffer. As the links are displaced from the position to be set,frictions are increased on the restricted portions. Strong restoringforces exerted on those portions further enhance the frictions, andso-called wedge effect is likely to occur to stick the links or exertexcessive stresses thereon. When the rail 100 is displaced from theposition to be set at the time of its holding and fixture, a reaction isapplied to the rail 100 and an excessive strain is likely to generatetherein.

With the remote control maintenance apparatus of this invention isprovided with a highly reliable control system in which the apparatus isnot stuck or exerted by an excessive stress when the real position andthe set position of the apparatus differ from each other.

FIG. 19 shows a block diagram for an embodiment of the whole system forcontrolling the remote control maintenance apparatus. General controlmeans 500 instructs the extension and housing of the rail 100, theoperation of the manipulator 330 and the like in each sequence. Means510 for generating commands sets the command values of the positions andthe driving forces of the driving axes according to the instructions ofthe general control means 500 in order to realize the predeterminedoperation of the apparatus. Means 510a, 510b, 510c, 510d and so on forcontrolling servo motors control respective servo motors 530a, 530b,530c, 530d and so on according to the command values, feedback signalsof means 540a, 540b, 540c and 540d and so on for checking rotationalangles which means are mounted on the respective servo motors, andsignals for checking the driving forces.

Means 550 for monitoring operation receives data of the rotationalangles and speeds of the servo motors 530a, 530b . . . / picked up bythe servo motor controlling means 520a, 520b, 520c, 520d and so on. Themeans 550 judges whether the servo motors operate normally and sends theresults to the general control means 500. Means 560 for checking theposition of the apparatus carries out the checking of the relativepositions of the elements to be controlled when the mechanisms in theremote control maintenance apparatus cooperate with each other, and themeans 560 sends the checked signals to the operation monitoring means550.

Means 570 for performing changeover after performing control(hereinafter referred to as the performing changeover means 570")selects one of the controls which have already prepared and are used inthe servo motor control means 520a, 520b . . . . The controls relate tothe positions controlled at a high rigidity, the positions controlled ata low rigidity, forces, torques, servo-off, brake-on and the like. Whenthe element to be controlled is displaced after it has been set atposition, the restoring force is exerted thereto by the correspondingservo motor. The position control at a high rigidity is defined as aposition control made by a high restoring force, that is, the positioncontrol made at a high servo rigidity. On the other hand, the positioncontrol at a low rigidity means the position control made by a lowrestoring force.

The operation of the remote control maintenance apparatus will now beexplained with reference to FIGS. 7, 9 to 11, 13, 15, 16, 18 and 19.

(i) The Operation for Transferring the Arcuated Links Constituting theRail Into the Torus Space

A servo motor 530m of the driving means of the vehicle 300, a servomotor 530rh for driving the slide of the joint roller holder 210 and aservo motor 530rc of the rail carriage 202 are position-controlled bycorresponding servo motor controlling means 520m, 520rh and 520rc andsynchronously driven.

When, for example, the arcuated links are excessively fed by the vehicle300 in the circumferential direction of the rail 100 due to themanufacturing tolerances and the displacement of the positions of theelements of the rails, contacting force between the joint rollers 103 onthe lower ends of the corresponding joints 102 and the side walls of theguide groove in the upper surface of the slide link 203 is increased andthe driving force for feeding the rail by means of the vehicle 300 isalso enhanced. As a result, the friction between the joint rollers 103and the side walls of the guide groove is increased so that the arcuatedlinks 101 are not moved smoothly. The servo motor controlling means 520mfor controlling the rail feeding movement of the vehicle 300 detectsthat the driving force exceeds a predetermined value, the positionaldisplacement is increased and the speed is reduced, and the generalcontrol means 500 receives signal indicating that the arcuated links 101do not move smoothly. The general control means 500 produced theincreased command values of movement of the joint roller holder 210 andrail carriage 202 by a proper values through the command generatingmeans 510 or moves back the rail carriage 202 by a proper value alsothrough the command generating means 510, whereby making the movement ofthe arcuated links 101 normal.

FIG. 9 shows the next step of the extension of the rail 100. While thedriving means for the vehicle 300 is stopped, the joint roller holder210 is made slide toward the center of the torus space 2, and at thesame time, the rail carriage 202 is caused to slide along the secondslide link 204 by the same distance as the joint roller holder 210. Allactuated links 101 on the first and second slide links 203 and 204 aremoved toward the center of the torus space 2, the link 101b rotatesabout the joint 102a to take the transient state as shown in FIG. 10 andthe final state as shown in FIG. 11. The links 101a and 101b assume acontinuous arc having a center substantially consistent with the centerof the torus space 2. In this step, the joint roller holder 210 and therail carriage 202 are controlled until they arrive at the positions neartheir positions shown in FIG. 11. The positional information at thesepositions is transmitted to the general control means 500 through theoperation monitoring means 550. The general control means 500 changesthe control mode of the servo motor control means 520rh and 520rc of thejoint roller holder 210 and the rail carriage 202 through the performingchangeover means 570 and the means 500 drives them by keeping thedriving forces lower than predetermined values. After then, theoperation monitoring means 550 detects that the speeds of the elementsto be controlled are rapidly reduced and the driving forces thereof areincreased to assume the state as shown in FIG. 11. When this occurs, thegeneral control means 500 stops the movement of the elements to becontrolled. Since this control allows the arcuated link 101b to reachthe state accurately as shown in FIG. 11 even if there are dimensionalerrors in the elements and the positional displacement and the run-overof the elements is not forcibly controlled, excessive forces are notapplied to the vehicle 300 supporting the arcuated link 101a and thelike. After the joint 102a of the arcuated link 101 has been locked, thearcuated link 101b is fed and the rail carriage 202 is moved toward thecask 8 in a synchronous manner. When the driving force of the railcarriage 202 is controlled in accordance with a predetermined value andthe position control at a low rigidity is carried out in this state, thejoint 102b arrives at the rotating axis of the support arm 205 to assumethe state as shown in FIG. 13. This control prevents the rail carriage202 from pulling the arcuated links 101 toward the cask 8 by anexcessive force even if there are dimensional errors in the elements andpositional displacement.

(ii) The Operation for Extending the Last Arcuated Link in the TorusSpace

The explanation will now be made to the extension of the last arcuatedlink 101f which takes place around the joint 102e (full line in FIG.16).

First, at the time when the swing link 201 begins to rotate from thestate in which it is directed in the radial direction of the torus space2 according to the rotation of the arcuated link 101f, as shown in FIG.1, the positional control of the swing link 201 by means of the servomotor controlling means 520 through the performing changeover means 570is stopped, making the servo control set free. Thereafter, the railcarriage 202 is advanced similarly in case in which the other arcuatedlinks 101 were fed, and the joint 102e is similarly locked. Further,when two rails are used, the distal end of opposing semi-circularlyarcuated rail 100' which was extended through opposing maintenance port9 is fixed to the joint 102f. In this state, the swing link 201 is setfree or is position controlled at a low rigidity and the rail carriage202 is also position-controlled at a low rigidity so that the reactionis reduced even if the positional displacement occurs at the time offixing said another rail 100' to the joint 102f.

(iii) The Operation for Supporting the Rail by Means of the SupportingDevice After the Extension of the Rail

As shown in FIG. 15, the guide roller 254 contacts the undersurface ofthe rail 100 during the extension of the rail 100. After extension, theclamping mechanism 255 is operated by means of a driving mechanism (notshown) to hold the projection 109 formed between the links on the outerperiphery of the rail. In this step, the swing link 201 and the railcarriage 202 are set free or are position-controlled at a low rigidityso as to reduce the reaction when the rail clamping mechanism 255 of therail supporting device 250 is moved. The slide link 252 may beposition-controlled at a low rigidity.

After the distal end of the rail 100 has been fixed and supported, theelements having a function for supporting the rail, such as the swinglink 201, the rail carriage 202, the slide link 252 and the like areposition-controlled at a high rigidity or locked by means of a brake,thereby ensuring the rigidity of the extended rail 100.

(iv) The Operation for Exchanging the Diverter Plate

After the extension of the rail 100 in the torus space 2, the vehicleholding mechanism of the support arm 205 is released, and the vehicle300 is moved along the rail 100 by driving the driving mechanism of thevehicle 100. Upon reaching the position above the diverter plate 6 to beexchanged, the vehicle 100 is stopped. A telescopic arm 331 as shown inFIG. 18 is extended or shrunk and swung. Due to the operation with apredetermined number of degrees of freedom, an end effecter 333 is setto the diverter plate holding position. In the next step, the endeffecter 333 is operated to hold the diverter plate 6. The drivingmechanism of the end effecter 333 having the above-mentioned degrees offreedom is position-controlled at a low rigidity to reduce the reactiondue to the holding of the diverter plate 6. After the dive-rter plate 6has been held and lifted, the position con-trol is changed from the onehaving a low rigidity to the one having a high rigidity, whereby thediverter plate 6 is transported at a high mechanical stability. Thereplacement of the diverter plate 6 with a new one is effected under theposition control at a low rigidity, reducing the reaction due to themounting of the new diverter plate.

v) The Operation for Returning the Vehicle to the Position of theSupport Arm

When the vehicle 300 is returned to the position at which the arm 205 isdisposed after the vehicle 300 has driven along the extended rail 100and the required operation of the rail has been finished, the rigidityof the position control for rotating the support arm 205 and driving theslide link 203 and the rail carriage 202 is lowered so that excessiveforces do not applied to each other even if the positional displacementoccurs between the rail and the support arm 205.

(vi) The Operation for Restoring the Rail in the Cask

The rail 100 extended in the torus space 2 is received in the cask 8substantially in the reversal steps of the extension of the rail 100.The restoring operation is carried out by changing over the rigidity ofthe position control, and monitoring and controlling the driving forces.

The technical effects of this embodied control apparatus are as follows:

(a) Since the cooperating operations can be corrected by controlling thedriving forces and monitoring the operations by detecting variations ofpositions and speeds, the displacement of the elements to be controlledbetween the positions to be set and the real positions, the sticking ofthe arcuated links of the rail and the generation of excessive stressescan be avoided.

(b) The position control for rotating the swing link is set free at thetime when it is operated synchronously with the last arcuated link ofthe rail which is being extended and operated dependently. Thus thesticking of the elements to be controlled and the generation ofexcessive stresses can be prevented as in the item (a).

(c) When the rail is fixed at its distal end and supported at itscentral portion, the rigidity of the position control of the mechanismssupporting the rail is lowered. Accordingly, the reaction due to thefixture and the support of the rail is reduced, and excessive stressesare prevented from being applied to the mechanisms.

(d) Since the rail is position-controlled so as to be held in positionat a high rigidity after the rail has been fixed, mechanical stabilityof the rail is securely maintained.

(e) Due to the fact that the rigidity of the position control of thevehicle and the arm can be lowered upon holding and setting the diverterplate, excessive reaction can be avoided even if positional errors ofthe elements to be controlled occur. The operational stability isensured because the position control is changed to the one at a highrigidity upon transferring the diverter plate.

(f) When the vehicle is returned to the position of the support arm,excess stresses can similarly be prevented from being generated.

With this embodiment, the control apparatus uses servo motor controllingmeans for detecting driving forces. In addition thereto, sensors forforces or torques can be used in the driving mechanism. Synchronousoperations and cooperating operations other than those as explainedabove can be performed by the control apparatus, and the same technicaleffects as explained above can be attained.

Further, in the embodied remote control maintenance apparatus, thevehicle 300 can be provided with a manipulator for maintaining the armortiles.

7. The State in Which the Manipulator for Maintaining the Armor Tiles ofthe First Wall is Operated on the Vehicle

In FIG. 20, the manipulator 360 is mounted on a foldable lift 361 whichis movable vertically. The lift 361 is moved by a reciprocatingmechanism (not shown) in the maintenance port in which the railsupporting device 250 is inserted and is positioned under the rail 100.

The manipulator 360 mounted on the lift 361 comprises two rings 362 and363 overlapped on each other, driving mechanism for rotating the rings362 and 363 around their centers and a slide arm 364. The drivingmachanism for the rings is supplied power and control signal from thelift 36 through a connector (not shown). Each of the rings 362 and 363has inner a diameter larger than the circumscribed circle of the rail100 and is cut away through substantially 90°, as shown in FIG. 20. Oneslide ring 362 can be connected mechanically to the vehicle 300 and isprovided with a connecting mechanism (not shown) for effecting theconnection of signal lines and power lines. The other slide ring 363slidably supports the slide arm 364 of the a manipulator 360 and isprovided with a driving device (not shown).

Referring to FIG. 20, the lift 361 disposed under the rail 100 israised. The rail 100 enters the space defined in the slide rings 362 and363 through the cut-away portions thereof and is stopped at the positionat which its center coincides with the rotating centers of the sliderings 362 and 363. The vehicle 300 is driven toward the slide ring 362and is connected thereto by means of the connecting mechanism.

As the lift 361 is lowered, the connector between the manipulator 360and the lift 361 is disconnected, and then the lift 361 is retractedfrom the torus space 2. As the vehicle is driven, the manipulator 360 isoperated in the torus space 2 to be set at an arbitrary position at thewall of the torus space 2, thereby effecting the maintenance of thearmor tiles 7.

When the vehicle 300 passes over the joints 102 of the rail 100 themovable slide ring 363 is made completely overlapped on the fixed slidering 362, as shown in FIG. 21, so that the slide ring 363 does notinterfere with the joints 102, as shown in FIG. 21.

Referring to FIG. 22 to 29, the manipulator 360 mounted on the vehicle300 will now be explained in more detail.

FIGS. 23 and 24 are cross-sectional views along line B--B and line C--Cof FIG. 22, respectively.

As shown in FIGS. 23 and 24, the manipulator 360 has the partiallycut-away fixed ring 362 detachably connected to the distal end of thevehicle 300. A guide groove 369 is formed in the fixed ring 362 so as tobe extended in its circumferential direction. On the both cut-away endportions of the fixed ring 362 are provided blocks 368 to which rollers370a and 370b are pivoted. The rollers 370a and 370b are rotatablyinserted in a circumferentially extending guide groove 369 formed in thepartially cut-away slide ring 363 having the similar cut-away as that ofthe fixed ring 362. Between the fixed ring 362 and the slide ring 363 isprovided a gear case 373 connected to a driving motor 372 by means of areduction device (reduction gearing) 371. The gear case 373 is providedon its both lateral sides with a plurality of rollers 370c and 370dwhich are guided and rolled in the guide grooves 369 of the fixed ring362 and the slide ring 363. A bevel gear 376 meshing with bevel gears374 and 375 is fixed to output shaft of the reduction device 371. Shafts377 and 379 are rotatably supported on the gear case 373 by means ofbearings 378 and 380, respectively. The shaft 379 has one end fixed tothe bevel gear 375 and the other end fixed to a spur gear 384 engagingwith a spur gear 381 formed on the outer periphery of the slide ring363, and the shaft 377 has one end fixed to the bevel gear 375 and theother end fixed to a spur gear 384 engaging with a spur gear 382 formedon the outer periphery of the fixed ring 362.

As shown in FIG. 28, the connecting portion 364a of the slide arm 364 ofthe manipulator 360 is fixed to the central portion of the slide ring363. In FIG. 29, the distal end of the slide arm 36 of the manipulator360 is provided with a joint R1 for rotating the distal end of the slidearm 364 around the axis of a slide arm 364 and a joint S1 for rotatingthe first arm 365 around the axis perpendicular to the axis of the jointR1. On the distal end of the first arm 365 is provided a joint S2 forrotating a second arm 366 around an axis parallel with the axis of thejoint S1. On the distal end of the second arm 366 are provided a jointR2 rotating around an axis perpendicular to the axis of the second arm366, a swing joint S3 rotating around an axis perpendicular to the axisof the joint R2 and a pivotal joint R3 for rotating a tool 390 around anaxis perpendicular to the joint S3. Each of the joints R2, S3 and R3 hasa driving mechanism (not shown), and they constitute a wrist 367 havingthree degrees of freedom.

The operation of the manipulator mounted vehicle 300 will now beexplained.

When the fixed ring 362 and the slide ring 363 of the manipulator 360overlap with each other as shown in FIG. 22, their cut-away portionsenable the vehicle 300 to move along the rail 100, because the joints102 of the rail 100 and the supporting portion of the rail supportingdevice 250 do not interfere with the cut-away portions of the rings 362and 363.

In order to exchange the first wall 7 or the like, the vehicle 300 runson the rail 100 to be set to a predetermined position at which thejoints 102 and the rail supporting device 250 are not located. Then, theslide ring 363 is rotated through a predetermined angle by operating thedriving motor 372 so that the slide arm 364 of the manipulator 360 isdirected in the required direction.

As shown in FIGS. 23 to 27, when the driving motor 372 is rotated, thebevel gear 376 is turned via the reduction device 371, and the shafts377 and 379 are rotated in the reverse directions to each other throughthe bevel gears 374 and 375 meshing with the bevel gear 376. The spurgear 381 engaging with the spur gear 383 turns the slide ring 363through an angle β defined by the gear ratio between the spur gears 383and 381 with respect to the gear case 373, and the spur gear 382engaging the spur gear 384 turns the gear case 373 through an angle cdefined by the gear ratio between the spur gears 384 and 382 withrespect to the fixed ring 362 in the same direction as the slide ring363, with the result that the slide ring 363 rotates through an angle of(α+β) with respect to the fixed ring 362.

The slide ring 363 carrying the manipulator slide arm 364 is securelysupported by the fixed ring 362 by means of the rollers 370a, 370b, 370cand 370d inserted in and guided by the guide grooves 369 formed in theboth rings 362 and 363. In this connection, the manipulator 360 can bedirected around the rail at any required direction (from 0° to 360°).

Referring to FIGS. 28 and 29, the joints of the manipulator 360 areoperated by driving means (not shown) and change their posture in orderto have an access to the first wall 7 formed in the reactor. Themanipulator 360 has nine degrees of freedom defined by its rotationaround the axis of the rail 100, its extension and shrinkage, itsrotation about the axis of the slide arm 364, the swing of the first arm365, the swing of the second arm 366, three degrees of freedom obtainedby the wrist 367 and the running of the vehicle 300. The redundancy offreedom enables the manipulator to take several postures at which themanipulator is accessible to any part of the first wall 7. Therefor, thetool can reach any position which is close to the first wall 7 and atwhich the joints 102 of the rail 100 or the rail 100 itself is supportedby the rail supporting device 250, or the directions of the slide arm364 of the manipulator 360 is limited when the vehicle 300 is positionedat those positions.

The remote control maintenance apparatus used for a tokamak type nuclearfusion reactor and provided with the manipulator 360 explained above hasthe following technical advantages:

(a) The structure comprising a cut-away fixed ring 362 having thefreedom of rotation around the rail, a slide ring 363 having the sameshape as the fixed ring 362 and driving means for making a relativemovement between both rings enables the vehicle to run on the railwithout causing interference of the vehicle 300 with the elements suchas the rail 100, its joints 102 and the rail supporting device 250, andthe manipulator 360 can be used in any position where such elements arenot disposed.

(b) By using two series of gear trains driven by a single driving motor372, the rotation of the gear case 373 around the fixed ring 362 and therotation of the slide ring 363 around the gear case 373 are carried outseparately. Therefore, when the gear ratios are selected properly, thefixed ring 362, the slide ring 363 and the gear case 373 can be arrangedso that they are most strongly supported by each other.

(c) Forming the fixed ring 362 and the slide ring 363 in the same shapehaving a cut-away portion permits the rings to be fixed to or removedfrom the vehicle 300 after mounting the rail.

(d) The manipulator 360 has eight degrees of freedom except the runningof the vehicle 300 consisting of the rotation around the rail, theextension and shrinkage, the rotation around the slide arm, the swing ofthe first arm 365, the swing of the second arm 366 and the rotation ofthe wrist around the three axes. Thus, the tool is accessible to thewhole area in the reactor having D-shaped vertical cross section.Further, when the rotation of the manipulator around the rail is limiteddue to the interference with the joints of the rail and the railsupporting device 250, its redundancy allows for an access to therequired portion at the other position.

In this embodiment, the manipulator 360 is mounted on and detached fromthe vehicle 300 on the rail 100. However, it may be previously mountedon the vehicle 300.

FIG. 30 shows a modified vehicle 300' on both end portions of whichmanipulators 360 having the same structure as the one mentioned aboveare mounted. The two manipulators 360 cooperate to enhance theirefficiency. One of them can be provided with a monitoring device such asa camera.

The remote control maintenance apparatus according to this invention canuse a vehicle 300 provided with a manipulator 330 for exchanging thediverter plate as shown in FIGS. 20 to 22 and a manipulator 360 forexchanging the armor tiles as shown in FIG. 30, or a vehicle 300'provided with two manipulators 360 for exchanging only the armor tilesaccording to the operation to be performed.

When the rails are extended around the whole circumferential length inthe torus space by using two rail mounting devices, two vehicles eachrunning on the respective rail mounting devices through 180° in oppositedirections can be used. Various combination of vehicles can be selectedaccording to the operation to be performed. When one of the vehicles hasbecome out of order in case where two vehicles are used, the othervehicle can be used so as to rescue the one which is out of order.

8. The Way How to Guide the Cable

As explained above, the maintenance apparatus of this embodimentcomprises driving means and rail mounting mechanisms mainly consistingof first and second links 203 and 204, a rail carriage 202 and a vehicle300 or vehicles 300 and/or a vehicle 300' or vehicles 300'. Cables areconnected to the rail mounting mechanisms and are operated so as to movethe mechanisms. The ways how to operate the cable to the vehicle willnow be explained.

FIG. 31 shows the state in which the cable 400 is housed when the rail100 is contained in the cask. The cable 400 connected to the vehicle 300is supported by the later described cable supports 401 provided on thejoints 102 and extends along the links 101. The cable 400 passes overthe swing link 201 and crosses the slide link. Then the cable 400 passesbetween cable feeding rollers 402 provided on the rail carriage 202 andoperated by driving means (not shown) for taking off the cable 400 andis taken up through a cable feeding roller 402 by means of a cable drum403 provided with a driving mechanism (not shown) for taking up thecable 400. The cable 400 is connected to a control device (not shown).

The structure of the cable support 401 provided on the joint 102 willnow be described. As shown in FIG. 3, the cable support 401 has theopenable lever 404 which is normally closed and opened when it ispushed. The cable support 401 has a U-shaped cable receiver 405 which isrotatably supported on the support shaft 406. Rollers 405A are mountedon the arms of and the inner bottom of the cable receiver 405. Thesupport shaft 406 is supported by the joint 102 and is swingable aroundthe axis of the joint 102. A limiting mechanism (not shown) is providedso that the support shaft 406 is disposed on a line always passing thesubstantial center of the angle defined by the links 101 on both sidesof the joint 102 when the links 101 are swung.

The operation of the cable 400 for moving the rail 100 and the vehicle300 will now be explained.

When the distal end of the rail 100 is advanced in the maintenance port9 toward the center of the torus space 2, the cable is moved togetherwith the rail 100.

After the links 102 of the rail 100 have been arranged linearly and thelink 204 together with the rail carriage 202 has been moved into themaintenance port 9, the support arm 205 swings in the torus space 2. Thecable 400 is continuously taken off from the cable drum 403 until thesupport arm 205 is stopped at the predetermined position.

As the links 101 are swung about the associated joints 102 located atthe proximal end of the vehicle 300 upon extending the rail 100 in thetorus space 2, the cable 400 are sent by the cable feeding rollers 402and the cable drum 403 toward the center of the torus space 2 to assumethe state as shown in FIG. 32.

When the vehicle 300 extends the rail 100, the cable 400 is pulledtoward the cask by means of the cable feeding rollers 402 and the cabledrum 403 to assume the state as shown in FIG. 33. As the joint 102approaches the vehicle 300, the lever 404 of the cable support 401 isopened by a projection (not shown) formed on the vehicle 300 so that thecable 400 comes off the cable support 401 and only the rail 100 isextended.

As the vehicle 300 is moved toward the distal end of the rail 100therealong, the cable 400 is taken off by the cable feeding rollers 402and the cable drum 403. At the time when the vehicle 300 passes over thejoint 102, the lever 404 is opened by the projection (not shown) formedon the vehicle 300. The cable 400 is received by the cable receiver 405and is smoothly guided by means of the rollers 405A.

In the process in which the vehicle is moved toward the maintenanceport, the cable 400 is pulled in by means of the cable feeding rollers402 and the cable drum 403. When the vehicle 300 runs over the joint102, the lever 404 of the cable support 401 is opened so that it comesoff the cable support 401.

The above description made to the vehicle 300 is also applicable to thevehicle 300'.

The above-mentioned remote control maintenance apparatus according tothis embodiment has the following technical features:

(A) In the apparatus, the rail 100 comprising a plurality of arcuatedlinks 101 is housed in a folded state and the first and second slidelinks 203 and 204 are also housed in an overlapping state. Thus, thewhole apparatus can pass through a narrow maintenance port and can bestored in a limited space.

(B) Since the joints 101 cannot swing beyond the continuous arch definedby them when they are extended, an arcuated rail is easily formedwithout a complicated control.

(C) The vehicle 300 is fixed to the support arm 205 and supports thedistal end of the rail. Therefore, the rail 100 can be extended at therequired position by positioning the support arm 205 at the requiredangle.

(D) The vehicle 300 is not only moved along the rail by means of thedriving mechanism of the vehicle but also can be fixed to the supportarm 205 so that the extending of the rail 100 is facilitated. Thissimplifies the structure of the apparatus.

(E) Because the joints 102 are locked when the links 101 which the rail100 comprises form a continuous arc, the rigidity and the strength ofthe rail 100 are ensured. The locking mechanism is driven by the drivingdevice provided on the vehicle 300, simplifying the structure of thejoints. Further, a narrow rectangular projection is formed on the innerend of the support shaft portion of the hook. This structure allows therail to be extended without performing a special operation such as aretarding operation after the hook has been locked or unlocked, therebysimplifying the structure of the hook.

(F) The rail 100 are folded or unfolded by moving the joints 102 of therail 100 by means of the joint roller holder 210 and the rail carriage202. Thus, it is unnecessary to provide on the joints 102 any drivingmechanisms for folding or unfolding the rail 100. This simplifies thestructure of the joints 102.

(G) When the rail 100 is extended in the torus space, the undersurfaceof the rail is supported by means of the guide roller 254 of the railholding device 250. This makes the extension of the rail 100 stable andthe positional accuracy for extending the rail is ensured.

(H) After having been extended by half the circumferential length in thetours space, the rail 100 is supported by the rail supporting device 250projected from the adjacent maintenance port and the distal end of therail is held by the rail supporting device positioned from anothermaintenance port. With this structure, the rigidity of the rail isenhanced and the apparatus is operated stably, thereby rendering theapparatus miniaturized and light in weight.

When the distal end of the rail is fixed, it is unnecessary to swing theextended whole rail, thereby enabling the apparatus to be operated in astable state.

(I) The provision of another rail which is extended through themaintenance port diametrically aligned therewith and o which the vehicleruns improves the operational efficiency.

(J) Since the frame of the vehicle 300 has a channeled cross-section,the vehicle 300 can run without interfering with the joints 102 and therail supporting device 250. Further, it is unnecessary to retract therail supporting device 250 when the vehicle 300 pass, thereby therigidity of the rail is not lowered.

(K) The telescopic structure of the manipulator provided on the vehicle300 allows the manipulator itself to be moved in the maintenance port ina shortened state and to operate at a large stroke.

(L) The swingable movement of the manipulator around the axis along therail permits the end effecter to be set at an arbitrary position in thepredetermined operational area.

(M) Since the manipulator for 360 maintaining the armor tiles is fedthrough another maintenance port and is mounted on the vehicle, thevehicle driving mechanism and the rail mounting mechanism can be usedwhen the armor tiles are maintained, thereby simplifying the structureof the manipulator and allowing for a quick exchange between themaintenance of the diverter plate and the maintenance of the armortiles.

(N) The manipulator can be used in a wide operational area due the factthat the whole manipulator can be rotated around the rail.

(O) Eight degrees of freedom provided for the wrist 367 of themanipulator 360 allows the wrist 367 to have an access to any requiredposition in the torus space 2.

(P) The signals for the driving power which are required for driving themanipulator are transmitted from the vehicle to the manipulator via theconnecting mechanism. This arrangement simplifies the guidance of thecable connected to the vehicle 300.

(Q) In the system in which adjacent maintenance port is used throughwhich rail supporting device 250 is fed, the usage of the transportationof the diverter plate simplifies the structure and the operation of saidrail supporting device 250 and increases its operational efficiency.

(R) The provision of the cable supports on the links 102 of the rail 100prevents the cable from being excessively stretched or loosened ortangling together.

(S) The cable support is rotatably supported and the limiter is providesso that it is positioned on the central line of the angle definedbetween the adjacent links so that the cable is not caught between theadjacent links or is not excessively bent.

In the above-mentioned embodiment, another rail 100' projects fromdiametrically opposed another maintenance port so as to be extended inthe torus space in a continuous arc. Alternatively, only the railsupporting device 250 is inserted in said another maintenance port tofix the distal end of the first rail 100. When, therefore, nomaintenance is required over the whole length of the rail, the operationof the rail can be simplified.

In the above-mentioned apparatus, the manipulator for the armor tilemaintenance is inserted in said another maintenance port and is mountedon the vehicle 300 by means of the rings 362 and 363. In place of themanipulator, an inspection device or any other maintenance device can beused so that a variety of maintenance can be performed and theefficiency is enhanced.

Additional advantages and modifications will readily occur to thoseskilled in the art. Therefore, the invention in its broader aspects isnot limited to the specific details, and representative devices, shownand described herein. Accordingly, various modifications may be madewithout departing from the spirit or scope of the general inventiveconcept as defined by the appended claims and their equivalents.

What is claimed is:
 1. A remote control apparatus for maintaining atokamak type nuclear fusion reactor comprising a vessel having a torusspace and a plurality of maintenance ports extending radially andcommunicating with the outside of said torus space, and in-vesselcomponents arranged in said vessel, comprising:a rail comprising aplurality of arcuated links to be arranged in a circumferentialdirection and a plurality of joints for pivotally connecting theadjacent arcuated links; a vehicle running on said rail extended in acontinuous circular form with a center substantially coinciding with acenter of said torus space; and a manipulator mounted on said vehicle,for handling said in-vessel components; said manipulator comprising:(a)a circular fixed ring coaxial with an axis of said rail extendedcircularly and having a first side and a second side, said first sidebeing fixed to said vehicle and having a cut-away which is set at aposition at which said fixed ring does not interfere with said jointswhen the vehicle runs on said rail; (b) a movable ring mounted on saidsecond side of said fixed ring movably in a circumferential directionand having a cut-away; and (c) driving means for moving said movablering with respect to said fixed ring.
 2. An apparatus according to claim1, wherein said manipulator further comprises a slide arm slidable in anaxial direction with respect to said movable ring, a plurality of armsand joints having at least six degrees of freedom, and a tool fordirectly handling said in-vessel components.
 3. An apparatus accordingto claim 1, wherein said driving means comprises gear trains fortransmitting driving force to said fixed ring and said movable ring atpredetermined gear ratios.
 4. An apparatus according to claim 1, whereinsaid vehicle is provided with two of said manipulators.
 5. An apparatusaccording to claim 1, wherein said vehicle is provided with a secondmanipulator for handling heavy in-vessel components.